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Professor Barnes presents poster at AGU Fall Meeting in San Francisco
Changes in water, carbon, and nitrogen fluxes with the addition of biochar to soils: lessons learned from laboratory and greenhouse experiments
Rebecca T. Barnes, Bard Center for Environmental Policy, Bard College, Annandale-on-Hudson, NY 12504 (becca.barnes@gmail.com)
Morgan E. Gallagher, Department of Earth Science, Rice University, Houston, TX 77005; Kellogg Biological Station, Hickory Corners, MI 49060 (morgan.gallagher@rice.edu)
Caroline A. Masiello, Department of Earth Science, Rice University, Houston, TX 77005 (masiello@rice.edu)
Brandon Dugan, Department of Earth Science, Rice University, Houston, TX 77005 (dugan@rice.edu)
Zuolin Liu, Department of Earth Science, Rice University, Houston, TX 77005 (zl17@rice.edu)
Jennifer A. Rudgers, Department of Ecology & Evolutionary Biology, Rice University, Houston, TX 77005 (jrudgers@rice.edu)
The addition of biochar to agricultural soils has the potential to provide a number of ecosystem services; ranging from carbon (C) sequestration to increased soil fertility and crop production. It is estimated that 0.5 to 0.9 Pg of C yr-1 can be sequestered through the addition of biochar to soils, significantly increasing the charcoal flux to the biosphere over natural inputs from fire (0.05 to 0.20 Pg C yr-1). There remain large uncertainties about biochar mobility within the environment, making it a challenge to assess the ecosystem residence time of biochar. We conducted laboratory and greenhouse experiments to understand how soil amendment with laboratory-produced biochar changes water, C, and nitrogen (N) fluxes from soils. We used column experiments to assess how biochar amendment to three types of soils (sand, organic, clay-rich) affected hydraulic conductivity and dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) fluxes. Results varied with soil type; biochar significantly decreased the hydraulic conductivity of the sand and organic soils by a factor of 10.6 and 2.7, respectively. While not statistically significant, biochar addition increased the hydraulic conductivity of the clay-rich soil by 50% on average. The addition of biochar significantly increased the DOC fluxes from the C-poor sand and clay soils while it significantly decreased the DOC flux from the organic-rich soil. In contrast, TDN fluxes decreased with biochar additions from all soil types, though the results were not statistically significant from the clay-rich soil. These laboratory experiments suggest that changes in the hydraulic conductivity of soil due to biochar amendments could play a significant role in understanding how biochar additions to agricultural fields will change watershed C and N dynamics. We additionally conducted a 28-day greenhouse experiment with sorghum plants using a three-way factorial treatment (water availability x biochar x mycorrhizae) to explore how biochar amendment could alter water, DOC, and TDN fluxes from agricultural soils. Each treatment had 30 plants (total 240 plants) and leachate was collected daily from 1/3 of the watered plants (i.e. 33% and 17% of plants had leachate collected on watering and drought days, respectively). Results show that despite no effect on net primary production, biochar additions significantly decreased DOC and TDN fluxes from plants under both drought and sufficient watering conditions. In addition, it is likely these trends are due in part to a significant interaction between biochar and mycorrhizae. These preliminary results confirm the numerous ecosystem services to be gained by amending soils with biochar, ranging from C sequestration to reduced nutrient pollution in waterways. However, they also suggest that all soils are not equal: care must be taken in choosing sites for soil amendment of biochar.
12-07-2011
This event was last updated on 12-07-2011
Meet Our Faculty
Gautam Sethi teaches environmental and natural resource economics at Bard CEP. His research includes institutional mechanisms to improve water quality in Oaxaca, Mexico, and the impact of wind farms on residential property values in the U.S.
“What I value most about Bard CEP is its ability to challenge and reshape one’s views. I am constantly challenged, by my colleagues and students, to think of the world in ways I had not hitherto, and I hope to have a similar effect on their worldview.”—Gautam Sethi, Associate Professor, Bard CEP
Monique Segarra, assistant professor of politics, teaches environmental policy analysis and climate politics. Her research focuses on the intersection of natural resource management, climate change, and human rights in the global south and the politics of water reform in Oaxaca, Mexico.
“Working with graduate students at CEP has enriched my work as a political scientist. The interdisciplinary nature of the program deepens our students’ ability to analyze and think about the policy process and how the key driver of our time, climate change and adaptation, is shaping our future policy choices.”
“Working with graduate students at CEP has enriched my work as a political scientist. The interdisciplinary nature of the program deepens our students’ ability to analyze and think about the policy process and how the key driver of our time, climate change and adaptation, is shaping our future policy choices.”
